[view·edit·purge]Nova means "new" in Latin. A nova is a cataclysmic nuclear explosion caused by the accretion of hydrogen onto the surface of a white dwarf star. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months. During the 16th century, astronomer Tycho Brahe observed the supernova SN 1572 in the constellation Cassiopeia, describing it in his book De stella nova (Latin for "concerning the new star"), giving rise to the name nova.